GB608598A - Improvements in creaming of synthetic rubber latices - Google Patents

Abstract

Synthetic rubber latices comprising aqueous emulsions of polymers and copolymers of butadienes-1,3, are creamed by incorporating or forming in situ in the emulsion after polymerization, an alkali salt of an acid other than an acid containing 8 or more carbon atoms in the molecule, in amount only sufficient to increase the average particle size of the polymer particles in the dispersion without forming any substantial amount of macroscopic flocks of the polymerized material and creaming the dispersion after polymerization with a hydrophilic colloidal creaming agent. The term alkali salt includes alkali metal salts, ammonium salts, and salts obtained from amines such as methylamine, ethylamine, dimethylamine, diethylamine, trimethylamine, triethylamine, propylamine, dipropylamine, isopropylamine, diisopropylamine, butyl primary amines, amyl primary amines, hexyl primary amines, cyclohexylamines, piperidine, 1-methyl-piperidine; 2-, 3- and 4-pipecoline, methyl propylamine, methyl butylamine and methyl diethylamine. The preferred amines are those boiling below 160 DEG C. The salt may be formed in situ by adding hydrochloric acid or bubbling in carbon dioxide and then neutralising with caustic potash or ammonia. In a modification, ammonium chloride or acetate is added to the latex and then formaldehyde till the pH is reduced to between 4.5 and 6.5. The pH is then raised to above 9 by means of a volatile base. Other specified salts are sodium silicate, diammonium phosphate, potassium borate, potassium citrate and dimethylamine formate. The latices may be polymers of butadiene 1,3, isoprene, chloroprene, piperylene, or 2,3-dimethyl-butadiene-1,3, or from copolymers of these compounds with styrene, vinyl naphthalene, acrylic acid, methyl acrylate, methyl methacrylate, acrylonitrile, methacrylonitrile, methacrylamide, isobutene, methyl vinyl ether, methyl vinyl ketone or vinylidene chloride. Substances such as sodium abietate, dimethylammonium caproylate, sodium lauryl sulphate, the ammonium salt of cocoanut oil in fatty acids, and the reaction product of ethylene oxide and oleyl alcohol, may be added during the polymerization step; and stabilisers having the formula R-SO3-M where M is an alkali metal, hydrogen or ammonium and R is an organic radical having at least one group with more than 8 carbon atoms. The creaming agents may be alginates, locust seed or carob bean gum, pectates, Karaya gum, or Irish moss. Specification 588,992 is referred to.ALSO:Synthetic rubber latices comprising aqueous emulsions or polymers and copolymers of butadienes 1, 3, are creamed by incorporating or forming in situ in the emulsion after polymerization, an alkali salt of an acid other than an acid containing 8 or more carbon atoms in the molecule, in amount only sufficient to increase the average particle size of the polymer particles in the dispersion without forming any substantial amount of microscopic flocks of the polymerized material and creaming, the dispersion after polymerization with a hydrophilic p colloidal creaming agent. The term alkali salt includes alkali metal salts, ammonium salts, and salts obtained from amines such as methylamine, ethylamine, dimethylamine, diethylamine, trimethylamine, triethylamine, propylamine, dipropylamine, isopropylamine, di-isopropylamine, butyl primary amines, amyl primary amines, hexyl primary amines, cyclohexylamines, piperidine, 1-methyl-piperidine; 2-, 3- and 4-pipecoline, methyl propylamine, methyl butylamine and methyl diethylamine. The preferred amines are those boiling below 160 DEG C. The salt may be formed in situ by adding hydrochloric acid or bubbling in carbon dioxide and then neutralizing with caustic potash or ammonia. In a modification ammonia chloride or acetate is added to the latex and then formaldehyde till the pH is reduced to between 4.5 and 6.5. The pH is then raised to above 9 by means of a volatile base. Other specified salts are sodium silicate, diammonium phosphate, potassium borate, potassium citrate and dimethylamine formate. The latices may be polymers of butadiene 1, 3, isoprene, chloroprene, piperylene, or 2, 3-dimethyl-butadiene-1, 3 or from copolymers of these compounds with styrene, vinyl naphthalene, acrylic acid, methyl acrylate, methyl methacrylate, acrylonitrile, methacrylonitrile, methacrylamide, isobutene, methyl vinyl ether, methyl vinyl ketone or vinylidene chloride. Substances such as sodium abietate, dimethylammonium caproylate, sodium lauryl sulphate, the ammonium salt of coconut oil in fatty acids, and the reaction product of ethylene oxide and oleyl alcohol, may be added during the polymerization step; and stabilizers having the formula R-SO3-M where M is an alkali metal, hydrogen or ammonium and R is an organic radical having at least one group with more than 8 carbon atoms. The creaming agents may be alginates, locust seed or carob bean gum, pectates, Karaya gum, or Irish moss. Specification 588,992 is referred to.